Inventors:
Robert K. Hollenbeck - Fort Wayne IN
Roger C. Becerra - Fort Wayne IN
Brian L. Beifus - Fort Wayne IN
Richard S. Tatman - Tyler TX
William C. Hittie - Fort Wayne IN
Assignee:
General Electric Company - Fort Wayne IN
International Classification:
F25B 4702
Abstract:
An apparatus for use with a refrigeration system including a compressor for compressing a working fluid evaporated in an evaporator and condensed in a condenser. A control circuit initiates operation of a refrigeration cycle and initiates a defrost cycle in response to a defrost enable signal. The apparatus drives an air moving assembly moving air over the evaporator. A motor including a rotatable assembly is in driving relation to the air moving assembly. An energizing circuit selectively energizes the motor in response to the control circuit. A sensing circuit generates a speed/torque signal representative of a speed or a torque of the motor. A defrost initiating circuit generates the defrost enable signal when the speed/torque signal indicates that the speed is greater than a predetermined speed or the torque is greater than a predetermined torque. As a result, the defrost cycle is initiated in response to degradation of the refrigeration cycle as indicated by frost or ice on the evaporator which reduces air flow through the evaporator and increases static pressure. Other demand defrost apparatus and methods of initiating and sensing defrost cycles are also disclosed.